Previous Article | Next Article ![]()
Mol. Cell. Biol., 09 1996, 5147-5155, Vol 16, No. 9
FJ Kim, AA Beeche, JJ Hunter, DJ Chin and TJ Hope
We previously determined that amino acids 64 to 120 of human T-cell
lymphotropic virus type 1 (HTLV-1) Rex can restore the function of an
effector domain mutant of human immunodeficiency virus type 1 (HIV-1) Rev
(T. J. Hope, B. L. Bond, D. McDonald, N. P. Klein, and T. G. Parslow, J.
Virol. 65:6001-6007, 1991). In this report, we (i) identify and
characterize a position-independent 17-amino-acid region of HTLV-1 Rex that
fully complements HIV-1 Rev effector domain mutants and (ii) show that this
17-amino-acid region and specific hydrophobic substitutions can serve as
nuclear export signals. Mutagenesis studies revealed that four leucines
within the minimal region were essential for function. Alignment of the
minimal Rex region with the HIV-1 Rev effector domain suggested that the
position of some of the conserved leucines is flexible. We found two of the
leucines could each occupy one of two positions within the context of the
full-length HTLV-1 Rex protein and maintain function. The idea of
flexibility within the Rex effector domain was confirmed and extended by
identifying functional substitutions by screening a library of effector
domain mutants in which the two regions of flexibility were randomized.
Secondly, the functional roles of the minimal Rex effector domain and
hydrophobic substitutions were independently confirmed by demonstrating
that these effector domains could serve as nuclear export signals when
conjugated with bovine serum albumin. Nuclear export of the wild-type Rex
conjugates was temperature dependent and sensitive to wheat germ agglutinin
and was blocked by a 20-fold excess of unlabeled conjugates. Together,
these studies reveal that position-variable hydrophobic interactions within
the HTLV-1 Rex effector domain mediate nuclear export function.
Copyright © 1996, American Society for Microbiology
Characterization of the nuclear export signal of human T-cell lymphotropic virus type 1 Rex reveals that nuclear export is mediated by position-variable hydrophobic interactions
Infectious Disease Laboratory, Salk Institute, La Jolla, California 92037, USA.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»